The veterinary staff weighed her, conducted a well-baby check and the calf, which was breathing well, appeared healthy.

Those and other details were delivered Friday in a zoo news conference outside the elephant barn. Neither the public nor the news media was allowed to see mother or calf. Zoo officials said given the all-nighter, staffers were exhausted and they wanted Rose and her newborn to have time to recover and bond.

Rose-Tu and calf: New VideoThe Oregon Zoo's Rose-Tu gave birth to a female calf at 2:17 a.m. Friday and according to Kim Smith, zoo director, she "looks like she's going to be a real pistol."

Keepers returned the calf to Rose's side within 30 or 40 minutes, according to Kim Smith, zoo director. Keele said Rose dropped her head to the ground, getting at calf's-eye-level, to take a long look at her second offspring.

She seemed anxious and excited but apparently didn't repeat any of the dangerous behavior of 2008, when she kicked and stepped on her first calf, Samudra; he suffered no broken bones or internal injuries and they later bonded.

Last calf: Samudra, born to the same parents Aug. 23, 2008, weighing 286 pounds. He exceeds 3,800 pounds today.

Gestation: Typically 20 to 22 months; this one lasted more than 21 months.

Trouble: Rose-Tu was a first-time mother when Samudra was born. She'd never witnessed a birth. Shortly after delivering Samudra she went into a frenzy, kicking and stepping on him. Keepers separated them; when they were later reintroduced, Rose-Tu and Samudra bonded.This birth apparently went more smoothly.

Zoo's breeding history: Once the nation's top breeding program, the Oregon Zoo's elephants produced 27 calves from the 1960s to the 1990s, beginning with Packy, born April 14, 1962. Zoo visitors celebrated his 50th birthday this spring. Like zoos continent-wide, Portland's ran out of room and breeding stopped, from 1994 to 2005 in Portland's case. Zoos didn't reinvigorate programs until a study published in 2000 suggested that unless breeding resumed, so many Asian elephants would have died that by 2050 fewer than 20 would remain in North American zoos.

Oregon Zoo herd: Three cows, three bulls, a 4-year-old male, plus the newborn.

First months: Calves typically lose weight the first week, then gain about two pounds a day. They can nurse up to five years but supplement mother's milk with solid food -- fruit, vegetables, hay -- after 10 or 12 months.

Attendance: The zoo saw record-breaking attendance the first month Samudra went on exhibit.

More on Rose-Tu: Before she was born, zookeepers and veterinarians didn't know that her mother, Me-Tu, carried twins, a rare condition typically fatal to mothers and calves. She gave birth to Rose-Tu and about eight hours later delivered another calf, which survived only an hour.

New exhibit: The $125 million bond voters passed in 2008 called for an expanded and improved elephant enclosure. Dubbed Elephant Lands, it will grow from 1.5 acres to 6 acres, and will give the pachyderms an array of opportunities to choose how they spend their time. Bulls, for instance, will have chances to drift in and out of the herd as they choose. Construction, due to begin next year, could wrap up by Dec. 1, 2014.

Off-site facility: The bond measure also called for an off-site reserve, where zoo elephants would have more room to roam when not on exhibit. A feasibility study for the facility is complete and planning is under way. Roslyn Lake, drained in 2008 when Portland General Electric decommissioned the Little Sandy Dam, is considered the most promising site, but Metro, which operates the zoo, hasn't purchased it or other land. Plus, the zoo hasn't figure out where it will get the operating expenses once the facility is built.

About two hours after the birth, the calf first nursed "and she had a good bout about 8 a.m.," Keele said.

The zoo has had elephant keepers on duty 24 hours a day since last weekend and they'll keep up that routine for an undetermined number of days.

While the staff is upbeat about a successful birth, they still have plenty of worries.

They'll monitor Rose for infection and at some point will draw blood from the calf to check for abnormalities.

Mortality is high among elephant calves; one chief concern is elephant endotheliotropic herpes virus, which can cause fatal hemorrhagic disease.

Perhaps a few days from now, keepers will allow the other two cow elephants and Samudra into the same space with Rose and the newborn. They've been segregated since late Thursday but have visual and tactile access to mother and calf: They can see through and reach their trunks through a "howdy gate," as the barrier separating them is known.

At one point during Rose's labor, Keele said, Samudra wrapped his trunk around a bunch of hay and reached it through the gate's bars toward his mother, as if offering something to ease her troubles.

She declined the gift.

Rose was tethered during the birth, but by Friday afternoon, Keele said, she and the new calf were freely wandering the room that has served as maternity suite for 50 years, since Packy was born there in 1962.

It never will be again, Smith said, using the calf's arrival as an opportunity to trumpet upcoming big changes to the elephant exhibit, which will be dramatically expanded and rebuilt; opening of the new exhibit is expected in December 2014.

Zoo officials haven't determined when they'll allow the public in to see the newcomer.

"Rose
should allow the calf to nurse regularly, sleep, play and generally act
like a calf without trying to stop it and control its movements," said
Bob Lee, elephant curator. "Then we'll determine whether she's calm and
comfortable with staff around. And finally, we want to make sure the
calf has had a chance to bond with the rest of the herd."

In the summer of 2008, visitors were first allowed to see Samudra when he was about 1 week old.

That
Saturday, the zoo allowed 30 visitors at a time to spend five minutes
in the indoor viewing area. They were asked to speak softly, if at all,
and asked not to use a flash if shooting still photography or videotape.

Keepers
expect to choose a short list of possible names for the newborn, then
give the zoo fans an opportunity to vote for their favorite online, as
they did after Samudra was born in 2008.